The present invention relates to a refractory, ceramic, shaped member for supplying gas and/or solids to molten metal in a metallurgical vessel. Shaped members of this type are generally referred to as "nozzles".
Nozzles are preferably inserted in the wall or base of a metallurgical smelting vessel (for example a converter or ladle), generally via a nozzle brick, and serve for the injection of scavenging gases, especially inert scavenging gases such as argon, in order to treat the smelt for optimizing quality.
Nozzles of this general type are known, for example, from German Offenlegungsschriften Nos. 35 31 533, Wertz dated Feb. 19, 1987 35 27 793, Bender et al dated Feb. 12, 1987 35 31 534, Wertz dated Feb. 19, 1987 and 35 20 783 LaBate dated Dec. 11, 1986. In addition, German Offenlegungscchrift No. 35 20 207 Winkelmann et al dated Dec. 11, 1986 discloses a nozzle that is intended for injecting gases or solids into a ladle containing molten metal. The single FIGURE of this last-mentioned reference, which deals exclusively with the mounting of the nozzle in the nozzle brick, shows a nozzle having a large, central passage through which gases or solids are to be injected. Such a nozzle with an extremely large passage cannot be used in practice, because with such a large passage, molten metal would readily enter the nozzle and would destroy the device.
However, there is a pressing need for also being able to inject solids into molten metal, especially for the purpose of desulfurizing the metal. Such solids include fine lime or mixtures of fine lime and soda, as well as calcium carbide (CaC.sub.2) or calcium cyanamide (CaCN.sub.2).
Solids, no matter how fine they are, cannot be injected via heretofore known gas nozzles, as they are summarized, for example, in "Radex-Rundschau, 1987, 288", because the fine porosity of such gas nozzles would rapidly lead to a blockage, and hence to a non-functionality, of the device. Furthermore, there would be the great danger that the molten metal would infiltrate as soon as the gas pressure was somewhat reduced.
Therefore, for the most part at present so-called injection or immersion lances are use for injecting solids; such lances are disclosed, for example, in German Gebrauchsmustern 86 22 299 dated Nov. 13, 1986 or 86 26 930 dated Jan. 8, 1987. Not only inert gases but also additives of the aforementioned type are introduced into the molten metal via such injection lances. For this purpose, the injection head and the major part of the casing of the injection lance are immersed in the molten metal. The gas and/or solid material is introduced into the molten metal via the so-called lance core, which is generally a steel pipe that opens out in the injection head via appropriate outlets.
That part of the injection lance that is immersed in the molten metal is subjected to considerable thermal and mechanical stresses, with repeated reference being made to this situation in the aforementioned German Gebrauchsmustern. However, if, for example, cracks or fissures reach the core of the lance, the injection lance is no longer usable and must be replaced. The worn out lance cannot be reused, despite the fact that a considerable portion of the casing would still be functional.
Numerous experiments in the past have therefore dealt with the mechanical stabilization of such injection lances.
A particular problem with this is that when the lance is emersed in the molten metal bath, and during the injection process, considerable oscillating movements, and hence high pressing forces, occur due to the displacement of the liquid; these forces must be absorbed without damage occurring to the lance, and in particular to the refractory casing. However, in practice this problem cannot be taken care of with an injection lance that is freely immersed in molten metal via a so-called lance stand.
lt is therefore an object of the present invention to provide a possibility for the simple and reliable supply of gas and/or solid material to the molten metal of a metallurgical vessel in such a way that the mechanical problems encountered with injection lances do not occur, but at the same time, without the danger of blockages or of a break-through of the molten metal, solids can be readily introduced into the molten metal. It is furthermore an object of the present invention to be able to introduce, preferably via a single device, both gases as well as solids, even in combination if necessary.